A simultaneous improvement of both strength and ductility by Sn addition in as-extruded Mg-6Al-4Zn alloy

Commercial wrought Mg alloys normally contain low alloying contents to ensure good formability. In the present work, high-alloyed Mg-6Al-4Zn-xSn (x = 1, 2 and 3 wt.%, respectively) alloys were fabricated by extrusion. Hereinto, Sn was proven to play an effective contribution to simultaneous improvement in strength and ductility that are traditional trade-off features of synthetic materials. It was found that the average grain size of those alloys decreases significantly from similar to 11 to similar to 4 mu m as a function of Sn contents increasing from 0 to 3 wt.%, while the amounts of Mg2Sn and Mg17Al12 particles continuously increase. More importantly, the addition of Sn leads to the transformation of dominated deformation modes from (10 (1) over bar2) extension twinning (1 wt.%) to pyramidal < c+a > slip (3 wt.%) during tensile tests along the extrusion direction at room temperature. The advantageous combination of ultimate tensile strength (similar to 366 MPa) and elongation (similar to 19%) in Mg-6Al-4Zn-3Sn alloy is mainly attributed to the strong strain hardening ability induced by the enhanced activity of non-basal < c+a > slip. This work could provide new opportunities for the development of high-alloyed wrought Mg alloys with promising mechanical properties. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.